This invention relates to hand stamps and more particularly to a hand stamp that is received by the user as a self-contained pre-inked hand stamp that does not require the use of a separate stamp inkpad.
Most conventional stamps require manufacturing a stamping member from rubber or other flexible material. The stamping member is mounted on a handle that is grasped by the user. The stamping member is placed into contact with ink, usually contained in an inkpad. The inked stamping member is then pressed against the surface onto which the stamp image is to be transferred. Repetition of the stamping process required that the stamping member be pressed against the inkpad each time an image is to be transferred. This is a disadvantage to the user as it requires extra time for each re-inking step and slows down the stamping process if many stampings are to be done. It also requires the use of a separate inkpad that must be periodically re-inked.
An improved stamp was developed. This used a stamping member made from a permeable foam material that allowed ink to pass through the stamping member. The ink was held within the stamp and allowed to gradually ooze onto the stamping member. This eliminated the need for a separate stamp inkpad.
This type of stamp pad is illustrated in U.S. Pat. No. 5,942,312 issued to Venkataraman et al. This patent discloses a pre-inked thermoplastic foam which has open cells in the area that is designed to transfer ink and closed or sealed cells in the area which is designed to be impermeable to ink. The inkpad is pre-inked before the image is formed on the thermoplastic material. Thus if there is a problem with the image, the entire pad including the ink, is wasted. Furthermore there may be difficulties in forming an image on a pre-inked pad as it may be messy or require special handling due to the ink in the pad.
Hand stamp users preferred the ease and convenience of the pre-inked stamps. A separate inkpad with its inherent mess was no longer required. The stamp manufacturers now had the problem of creating the image on the foam stamp surface and pre-inking the stamp so that it was ready for use by the user. An improvement to creating the image on the stamp foam surface is illustrated in U.S. Pat. No. 5,858,298 issued to Leo Humal. This patent discloses a method to make the image on the surface of a porous thermoplastic material by heat sealing portions of the surface to define the image. In order to use the thermoplastic stamp surface, it is necessary to provide an ink cartridge with a supply of ink against the porous thermoplastic stamp material. One approach to pre-inking the stamp was to use a pre-inked cartridge. The pre-inked cartridge was shipped to the stamp manufacturer in a sealed airtight bag. The stamp manufacturer would cut the bag, carefully remove the pre-inked cartridge, place it in contact with the porous thermoplastic stamp surface, and allow the ink from the cartridge to migrate through the porous stamp surface. This generally took up to one hour for the ink migration to occur so that the stamp could be used. Thus the process was time consuming. The process was also still messy in that the cartridge had to be carefully removed, usually using tweezers or gloves.
Yet another problem was the large inventory of pre-inked cartridges required to be carried by the stamp manufacturer. A different size cartridge is required for each stamp size. In addition, each color offered must be stocked for all of the stamp sizes. This resulted in a large number of pre-inked cartridges being held in inventory.
Applicant's invention addresses and solves the problems of the prior art devices. It also has several advantages over the prior devices. The invention comprises a new and improved ink cartridge that is received into the hand stamp. The ink cartridge and foam stamping member are mounted in the hand stamp by means of a trim ring. The foam stamping member is made of a porous foam material. There are ink impermeable portions and open portions on the foam stamping member that define an image. A non-inked (dry) ink cartridge having a center portion removed is provided. The ink cartridge is placed on the backside of the foam stamping member in the trim ring. The proper color ink is then poured into the removed center portion of the ink cartridge. The ink migrates into the foam stamping member and the ink cartridge. The center portion that was removed from the ink cartridge is reinserted. The trim ring is then inserted into the hand stamp which is ready for printing. In an alternate arrangement, the foam stamping member is provided with a second layer of ink absorbing foam material that rapidly absorbs ink when it is poured into the removed center portion of the ink cartridge.